VC发邮件返回错误：500Error:bad syntax，请问大虾们怎么解决？？急急！！！

用VC做个发信的程序，前段时间也能正常发信，但是这段时间返回的代码也是发送成功，但是邮箱里不到，
From: [email protected]
PA: 1234456
To: [email protected]
Object: ddddconnect received  220HELLO AAA
auth login received 334
Nzc1Mjg1MjEA received  235
MAIL FROM :[email protected]
RCPT TO:[email protected]
received 250
DATA received  354
body received  250可是信箱没有受到信件，我试过很多次了，最后发现是500Error:bad syntax
请问大虾们怎么解决？？急急！！！
谢谢